Power management in a power over data network

ABSTRACT

A method of managing power in a power over data network, the method includes, obtaining a first request for modification of a power consumption profile of a device connected to the network, when the modification entails a raise in the power consumption profile, determining whether the first request can be satisfied with regards to a current consumption situation over the network, and when it is determined that the first request cannot be satisfied, triggering a broadcast over the network of a second request for lowering a power consumption profile of at least one device connected to the network, and getting back to said determination step.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a National Phase application of InternationalPatent Application No. PCT/EP2016/081749, filed Dec. 19, 2016, entitled“Power management in a power over data network”, which claims priorityto United Kingdom Patent Application No. 1522546.9, filed on Dec. 21,2015, all of which are hereby expressly incorporated by reference hereinin their entirety.

FIELD OF THE INVENTION

The present invention relates to power over data network, in particulardigital video surveillance systems.

More particularly, the present invention relates to video systems usingpower over data cables (such as Power over Ethernet “PoE” and Power overCoax “PoC”) to distribute the power from a central point to thesurveillance cameras.

BACKGROUND OF THE INVENTION

Power distribution over data cables is a very interesting techniquesince it saves the costs of a dedicated power network in parallel of thedata network or expensive battery solutions.

However, the total power that can be carried using power distributionover data cables is limited and the power loss in the cable is highbecause of the relatively low voltage that is carried (typically 48 to56 volts). On the contrary, power distribution networks carry 110 to 220volts and therefore they are less prone to power loss. However, theyrequire AC/DC converters to power the devices.

The systems relying on power distribution over data cables are calledpower constrained systems.

The power is constrained at two levels.

The first level is the port level. A switch or other network equipmentmakes it possible to deliver only a maximum amount of power on a singleport. This usually limits the type of device that can be powered.

The second level is the switch or network equipment level. The sum ofper port available power shall be sustained by the device's own powersupply.

Video surveillance camera manufacturers provide documents with themaximum and typical power consumption of their devices. Such informationis used by system integrators for power supply dimensioning. Often, themaximum power consumption specification is a conservative FIG. and ishigher than what is actually consumed by the camera.

Cameras power consumption can be sorted into three power consumptionlevels:

-   -   the lowest power consumption level is when the camera is in the        lowest resolution mode,    -   the typical power consumption level is when the camera is in        high resolution mode,    -   the maximum power consumption level is when the camera motors        are in action (for PTZ (“Pan-Tilt-Zoom”), optical zoom, . . . )        or when an internal electrical heater is used.

Based on this categorization, a power constrained video surveillancesystem performance can be characterized by a combination of threecriteria:

1. The coverage: the more cameras are used, higher is the area coveredby the video surveillance system.

2. The resolution: the image resolution of each camera defines thesystem global resolution.

3. The adaptability: PTZ cameras and mechanical optical zoom increasesthe system adaptability to changing conditions or allow to compensatefor a lower coverage rate.

In a power constrained video system, it may not be possible to raiseeach of the three criteria simultaneously to the maximum.

In document “SensEye: A Multi-tier Camera Sensor Network”, ofPurushottam Kulkarni, Deepak Ganesan, Prashant Shenoy and Qifeng Lu,Department of Computer Science, University of Massachusetts, Amherst,Mass. 01003, there is described a hierarchical system wherein lowresolution cameras can wakeup sleeping high resolution cameras that itturn can wakeup sleeping PTZ cameras. The wakeup event is based onmotion detection.

This system is particularly well adapted for systems based on batterypowered cameras. Each high battery consumption camera (high resolutionand PTZ) is sleeping unless waken up by a low resolution camera whenneeded. Thus, the lifetime of the batteries is extended.

However, this system does not match the requirements of powerconstrained systems since it not designed to keep the power consumptionwithin a given power budget. All cameras can be set to worksimultaneously since they are battery powered and thus not subject topower shortage from a shared power supply source.

Ethernet PoE switches are usually based on priority levels. The switchmay not be able to supply power to all connected devices if the totalpower needed exceeds a certain threshold. Priority levels are used fordetermining which ports are allowed to supply power. When ports have asame priority, the port which has the lowest number is given higherpriority.

This solution is static and is not useful for discriminating the powerprofile of each camera.

Thus, the inventors brought into light the fact that there is still aneed for improved power network systems. In particular, there is still aneed for power management techniques that make it possible todynamically extend coverage and/or resolution and/or achieveadaptability in power constrained video monitoring systems.

The present invention lies within this context.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a methodof managing power in a power over data network, the method comprisingthe following steps:

-   -   obtaining a first request for modification of a power        consumption profile of a device connected to said network,    -   when said modification entails a raise in said power consumption        profile, determining whether said first request can be satisfied        with regards to a current consumption situation over the        network, and

wherein, when it is determined that said first request cannot besatisfied:

-   -   triggering a broadcast over the network of a second request for        lowering a power consumption profile of at least one device        connected to said network, and    -   getting back to said determination step.

Embodiments make it possible to manage power distribution in power overdata networks in an efficient manner.

By virtue of these features, before of modifying the power consumptionprofile of a device, the global power budget situation of the network ischecked. Thus, the global power budget of the network is never exceeded.

According to a feature, said modification entails a drop in said powerconsumption, the method comprises triggering:

-   -   said modification of said power consumption profile, and    -   a broadcast of a message over the network identifying said        modification of said power consumption profile.

Thus, the global power budget of the network being not exceeded by thismodification of power consumption profile, the device modifies its powerconsumption profile.

In addition, all devices in the network are informed of the change ofpower consumption profile of a device.

According to a feature, said triggering of said modification of saidpower consumption profile comprises sending a request for modificationof said power consumption profile to said device connected to saidnetwork.

Thus, the power budget is managed in a centralized manner allowingcomplex management algorithms to be used.

According to a feature, said first request is received through a userinterface of a device of the network.

According to a feature, first request is triggered by a power profileselection by a user in said interface.

Thus, an operator may change the power consumption profile of thedevices of the network.

According to a feature, when it is determined that said first requestcan be satisfied, the method further comprises triggering:

-   -   said modification of said power consumption profile, and    -   a broadcast of a message over the network identifying said        modification of said power consumption profile.

Thus all devices in the network have real-time information about powerbudget changes in the network.

According to a feature, said second request is sent to all devicesconnected to the network, said second request triggering a minimizationof power consumption profile of each device receiving the request.

According to a feature, said second request is sent successively tocandidate devices after successive determinations of whether said firstrequest can be satisfied with regards to a current consumption situationover the network.

The device thus releases only the needed amount of power.

According to a feature, said second request triggers a minimization ofpower consumption profile of each device receiving the second request.

Thus, the response to the request for lowering the power consumptionprofile is faster.

According to a feature, said second request triggers an incrementallowering of power consumption profile of each device receiving thesecond request.

Thus, the power is lowered equally among all devices in the networkreceiving the request for lowering the power consumption profile.

According to a feature, the method further comprising emitting a messageindicating that said first request cannot be satisfied.

Thus, troubleshoot of the system is easy.

According to a feature, said triggering of a broadcast over the networkof a second request for lowering a power consumption profile comprisesemitting a message indicating that said first request cannot besatisfied.

Thus, the power status of the system may be monitored.

According to an embodiment, said network comprises a plurality ofdevices controlled by a control device, and wherein said method iscarried out by each of the devices.

Thus the method being carried out by each of the devices of the network,the processing is distributed among the devices of the system.

According to another embodiment, said network comprises a plurality ofdevices controlled by a control device, and wherein said method iscarried out by said control device.

Thus, the complexity of the devices is low.

According to a feature, said network comprises a plurality of devicescontrolled by a control device, and wherein said message indicating thatsaid first request cannot be satisfied is sent by a device to thecontrol device, said broadcast over the network of a second request forlowering a power consumption profile is sent by said device and theother steps are carried out by said devices.

Thus, the processing is distributed among the devices of the system.

According to a feature, said network is a video surveillance network,said devices are cameras and said control device a video monitoringsystem.

According to a feature, the method further comprises the followingsteps, when a device is newly connected to the network:

-   -   broadcasting a message comprising power profile characteristics        of the device newly connected to the network,    -   receiving, in response to said message, at least one power        profile information message from at least one device connected        to the network, said at least one power profile information        message comprising power profile information concerning said at        least one device connected to the network, and    -   determining a current consumption situation over the network        based on said received at least one power profile information        message from at least one device connected to the network.

Thus, troubleshoot at a new device start-up is easy and anunder-dimensioned power supply for the system may be detected.

According to a feature, the method further comprises:

-   -   determining whether it is possible to lower the power profile of        the device newly connected to the network with regards to the        determined current consumption situation over the network, and    -   if the power profile cannot be lowered, emitting an alert        message indicating that at least one power consumption will not        be satisfied on the network.

Thus, when a power profile of the device newly connected to the networkcannot be lowered, troubleshoot of the system is easy, even when adevice is connected without starting-up the whole system, that is whenthe device is «hot plugged».

According to a feature, the method of managing power in a power overdata network is performed by a monitoring device of the network, themethod comprising the following steps

-   -   determining that a first request for modification of the power        consumption profile of a device connected to the network cannot        be satisfied, when said modification entails a raise in said        power consumption profile, and    -   repeatedly broadcasting over the network a second request for        lowering the power consumption profiles of the other devices        connected to the network, said second request being repeatedly        broadcasted until said first request can be satisfied.

Thus, the complexity of the devices connected to the network is low.

According to a feature, said determining step comprises receiving, fromsaid device connected to the network, a message indicating said firstrequest for modification of its power consumption profile cannot besatisfied.

Thus, an operator may monitor the power status of the device.

According to a feature, said determining step comprises:

-   -   determining a current consumption situation over the network,        and    -   determining whether the modification of the power profile        according to the request is possible with regards to the        determined current consumption situation over the network.

According to a feature, the method further comprises transmitting to thedevice connected to the network, a message indicating that the firstrequest can be satisfied.

Thus, the power budget situation in the network may be monitored inreal-time.

According to a feature, the method of managing power in a power overdata network is performed by a device connected to the network, themethod comprising the following steps:

-   -   obtaining a first request for modification of a power        consumption profile of the device connected to said network,    -   when said modification entails a raise in said power consumption        profile, determining whether said first request can be satisfied        with regards to a current consumption situation over the        network, and

wherein, when it is determined that said first request cannot besatisfied:

-   -   triggering a broadcast over the network of a second request for        lowering a power consumption profile of at least one device        connected to said network.

According to a feature, said broadcasting is performed by said deviceconnected to the network and the method further comprises getting backto said determination step after the broadcasting.

According to a feature, said triggering step comprises:

-   -   transmitting to a monitoring device of the network a message        indicating that said first request cannot be satisfied with        regards to the current consumption situation over the network,        thereby enabling the monitoring device to perform the        broadcasting, and    -   receiving, in response to said message, a message indicating        that the first request can be satisfied.

Thus the power budget situation in the network is managed in acentralized manner allowing complex management algorithms to be used.

According to a feature, said device connected to the network comprises acamera device.

According to a feature, said device connected to the network furthercomprises a network adapter connected to the camera device by acommunication link.

Thus, since an adapter can be connected to various types of cameras,different types of cameras and of adapters may be used in the system,the system being flexible.

According to a feature, the method comprises, said device connected tothe network receive a request for modification of power consumptionprofile, and said network adapter sending a message (for example a“switch to power profile” message) to the said camera device containinga new power profile.

According to a feature, the method further comprising:

-   -   the camera device sending a first message (for example a “get        module power consumption” message) to said network adapter, and    -   the network adapter sending in response to said first message        (for example a “get module power consumption” message), a second        message (for example a “module power consumption response”        message) comprising the power consumption of the network        adapter.

Thus the power budget situation in the network can be calculated withgreater accuracy by taking into account the adapter power overhead.

According to a second aspect of the invention there is provided a deviceof managing power in a power over data network, the device comprising:

-   -   means for obtaining a first request for modification of a power        consumption profile of said device, said device being connected        to said network,    -   means for determining whether said first request can be        satisfied with regards to a current consumption situation over        the network, when said modification entails a raise in said        power consumption profile, and    -   means for triggering a broadcast over the network of a second        request for lowering a power consumption profile of at least one        device connected to said network when means for determining        determine that said first request cannot be satisfied.

According to a feature, the device further comprises means fortriggering:

-   -   said modification of said power consumption profile, and    -   a broadcast of a message over the network identifying said        modification of said power consumption profile,

when said modification entails a drop in said power consumption.

According to a feature, said means for triggering said modification ofsaid power consumption profile comprises means for sending a request formodification of said power consumption profile to one device connectedto said network.

According to a feature, the device further comprises means fortriggering:

-   -   said modification of said power consumption profile, and    -   a broadcast of a message over the network identifying said        modification of said power consumption profile,

when it is determined that said request can be satisfied.

According to a feature, the device further comprising means for emittinga message indicating that said first request cannot be satisfied.

According to a feature, said means for triggering of a broadcast overthe network of a second request for lowering a power consumption profilecomprises means for emitting said message indicating that said firstrequest cannot be satisfied.

According to a feature, said is controlled by a control device, saiddevice being configured for carrying out a method according to theinvention.

According to a feature, said device is a control device controlling aplurality of devices connected to said network, said control devicebeing configured for carrying out a method according to the invention.

According to a feature, the device further comprising:

-   -   means for broadcasting a message comprising power profile        characteristics of a device newly connected to the network,    -   means for receiving, in response to said message, at least one        power profile information message from at least one device        connected to the network, said at least one power profile        information message comprising power profile information        concerning said at least one device connected to the network,        and    -   means for determining a current consumption situation over the        network based on said received at least one power profile        information message from at least one device connected to the        network.

According to a feature, the device further comprising:

-   -   means for determining whether it is possible to lower the power        profile of the device newly connected to the network with        regards to the determined current consumption situation over the        network, and    -   means for emitting an alert message indicating that at least one        power consumption will not be satisfied on the network, if the        profile cannot be lowered.

According to a feature, the device comprises:

-   -   means for determining that a first request for modification of        the power consumption profile of a device connected to the        network cannot be satisfied, when said modification entails a        raise in said power consumption profile, and    -   means for repeatedly broadcasting over the network a second        request for lowering the power consumption profiles of the other        devices connected to the network, said second request being        repeatedly broadcasted until said first request can be        satisfied.

According to a feature, said means for determining comprises:

-   -   means for determining a current consumption situation over the        network, and    -   means for determining whether the modification of the power        profile according to the request is possible with regards to the        determined current consumption situation over the network.

According to a third aspect of the invention there is provided a cameradevice performing the method for managing power according to theinvention; said camera device being connected to a network.

According to a feature, the camera device connected further comprises anetwork adapter connected to said camera device by a communication link.

According to a feature, the camera device comprises:

-   -   means for sending a first message (for example a “get module        power consumption” message) to said network adapter, and    -   means for receiving in response to said first message (for        example a “get module power consumption” message), a second        message (for example a “module power consumption response”        message) comprising the power consumption of the network        adapter.

According to a fourth aspect of the invention there is provided anetwork adaptor connected to a camera device by a communication link,the network adaptor comprising means for sending a message (for examplea “switch to power profile” message) to said camera device containing anew power profile when said camera device receive a request formodification of power consumption profile.

According to a fifth aspect of the invention there is provided a systemcomprising a plurality of camera devices and a control camera device,the camera devices and the control camera device being according to theinvention, said network being a video surveillance network, and saidcontrol camera device a video monitoring system.

According to a sixth aspect of the invention there is provided a meansfor storing information which can be read by a computer or amicroprocessor holding instructions of a computer program, forimplementing a method for wireless communications according to theinvention, when said information is read by said computer or saidmicroprocessor.

The means for storing information may be partially or totally removable.

According to a seventh aspect of the invention there is provided acomputer program product which can be loaded into a programmableapparatus, comprising a sequence of instructions for implementing amethod for managing power according to the invention, when said computerprogram product is loaded into and executed by said programmableapparatus.

The objects according to the second, third, fourth, fifth, sixth andseventh aspects of the invention provide at least the same advantages asthose provided by the method according to the first aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the invention will become apparent from thefollowing description of non-limiting exemplary embodiments, withreference to the appended drawings, in which:

FIG. 1a schematically illustrates a video surveillance systemimplementing IP over Coax,

FIG. 1b schematically illustrates an Ethernet video surveillance system,

FIG. 2 illustrates exemplary information that may be displayed on a VMSscreen according to embodiments,

FIG. 3 schematically illustrates different embodiments of a surveillancecamera,

FIG. 3a schematically illustrates an integrated IP over coaxsurveillance camera according to embodiments,

FIG. 3b schematically illustrates an IP surveillance camera according toembodiments,

FIG. 3c schematically illustrates a modular IP over coax surveillancecamera according to embodiments,

FIG. 4a schematically illustrates data processed by a camera CPUaccording embodiments,

FIG. 4b illustrates the data stored in the IP over Coaxial adapter NVRAMfor power consumption according to embodiments,

FIG. 5a schematically illustrates messages that may be exchanged betweena camera and a VMS according to embodiments,

FIG. 5b illustrates the messages that may be exchanged between the IPcamera and the IP over Coax adapter according to embodiments,

FIG. 6 is a flowchart of steps carried out by a camera CPU or an adapterCPU when powered according to embodiments,

FIG. 6a is a flowchart of additional steps in step 601 of FIG. 6 whencarried out by an adapter CPU according to embodiments,

FIG. 6b is a flowchart of additional steps in step 601 of FIG. 6 whencarried out by a network processor according to embodiments

FIG. 7 is a flowchart of steps carried out by a camera CPU for powerbudget calculation and negotiation with other cameras according toembodiments,

FIG. 8 is a flowchart of steps carried out by a camera CPU for powerbudget checking upon receipt of a PP info Message according toembodiments,

FIG. 9 is a flowchart of steps carried out by a VMS CPU according toembodiments,

FIG. 10 schematically illustrates a VMS according to embodiments,

FIG. 11 schematically illustrates data processed by a VMS CPU accordingto embodiments,

FIG. 12 is a flowchart of steps carried out by a VMS CPU for powernegotiation according to embodiments,

FIG. 13 is a flowchart of steps carried out by a camera CPU for powerbudget calculation according to embodiments,

FIG. 14 is a flowchart of steps carried out by a VMS CPU for powerbudget calculation and for power negotiation according to embodiments.

DETAILED DESCRIPTION OF THE INVENTION

In what follows, embodiments of the invention are described in thecontext of a video surveillance system.

It is made possible for an operator to change the power profile of acamera from a video monitoring system (VMS). The operator may change thepower consumption profile of the devices of the network, in particular,the operator may:

1. Change coverage: request to turn on/off a camera (SLEEP profile),

2. Change resolution: request to increase/decrease the resolution of acamera (Low_res and High_res profile),

3. Change angle: request a PTZ move of a camera or a change of theoptical zoom setting (PTZ profile).

According to first embodiments, the power budget calculation and thepower negotiation are carried out by the cameras. Each camera thatreceives a command (or request) for changing its power profile that willresult in a raise of its own power consumption:

-   -   Checks the total power budget situation in the network,    -   If the power budget allows it, changes its power profile,        publish its new power status,    -   If the power budget does not allow it, repeatedly requests other        cameras to lower their power profile until success.

Each camera that receives a user command that will result in a drop ofits own power consumption profile publishes its new power profile to allcameras.

According to second embodiments, the cameras perform the power budgetcalculation and the VMS performs the power negotiation. Each camera thatreceives a command for changing its power profile that will result in araise of its own power consumption:

-   -   Checks the total power budget situation,    -   If the power budget allows it, change its power profile,        publishes its new power status,    -   If the power budget does not allow it, sends a negative        acknowledgement to the VMS.

Each camera that receives a user command that will result in a drop ofits own power consumption profile publishes its new power profile to allcameras

On the VMS side if a negative acknowledgement is received, then the VMSrepeatedly asks other cameras to lower their power profile until enoughpower has been cleared to send again a power profile change command tothe camera.

According to third embodiments, the power budget calculation andnegotiation are carried out by the VMS. The camera power budget isincreased to allow a power profile change for a given camera and then ifthe increased camera power budget does not fit into the system powerbudget then the VMS repeatedly asks the other cameras to lower theirpower profile until enough power has been cleared to send the powerprofile change command to the originally targeted camera.

First, embodiments wherein both the power budget calculation and thepower negotiation are carried out at a camera level are described.

FIG. 1a schematically illustrates an IP over Coax video surveillancesystem.

At the central point video surveillance system infrastructure, equipmentcalled “Receivers” 103 (Receiver 1) and 104 (Receiver 2) connect aplurality of cameras 108 (Camera 1), 109 (Camera 2), 110 (Camera 3), 111(Camera 4), 112 (Camera 5), and 113 (Camera 6) to a LAN infrastructure102.

Each receiver provides power to the cameras through coax cables 121, 122and 123. The Receiver encapsulates uplink IP LAN traffic received fromits LAN interface into packets suitable for digital data transport overCoax cables such as HomePlug AV packets and transmits them on the Coaxinterfaces. The Receiver also extracts IP LAN traffic from packetsreceived on the downlink coax interfaces and forwards them on the LANinterface.

The main coax cables can be used either for connecting one or severalcameras. For example camera 110 is directly connected to the main coaxcable 122 while cameras 109 and 108 are connected to the main coax cable121 by “T” style connectors. Such connectors can be used for extendingthe number of cameras connected to a main coax cable.

The LAN infrastructure 102 includes switches, routers and gateways fortransporting the IP video to the VMS (“Video Monitoring System”) 101.

The VMS (“Video Monitoring System”) 101 displays the IP video streamsfor the surveillance purpose. Also, the VMS 101 displays a userinterface enabling the operator to configure the cameras, to change thecameras power profile and to receive power alerts from the cameras.

One example of Receiver is the NV-ER1804 TBus™ from NVT™.

Receivers 103 and 104 are not represented in details in the present FIG.for the sake of conciseness. Only the power supply details are shown.

Receiver 103 gets power from a standard AC power outlet (110 or 220volts). The AC power is converted to DC power suitable for cameras (forexample 48 or 56 volts) by an AC/DC converter 106. In the presentexample, the AC/DC converter can handle up to 250 Watt of total power.The DC power is distributed from the converter 106 to each port (e.g.107). Each port has its own power protection to limit the amount ofpower that can be drawn from the port. In the present example, it can bedrawn up to 75 Watts from each port. However, the AC/DC converter 106cannot handle the situation where all ports would deliver their fullpower capacity.

Based on this receiver architecture, the cameras are sorted into portsets 114 (port 2), 115 (port 4) and 118 (port 3). The port sets are partof group sets 117 (group 1) and 118 (group 2).

Camera 108 and Camera 109 are part of port set 114 because they are bothconnected to the port “number 2” (port 2) of receiver 103. Thus, thesetwo cameras share a total power budget of 75 Watt.

Camera 110 is the single member of the port set 115 and has access to atotal power budget of 75 Watts from the port “number 4” (port 4) ofreceiver 103.

Also, all cameras of group set 117 share the total power capacity of thereceiver 103 (250 Watts in the present example). It means that the sumof the power consumed in each port set included in group set 117 mustnot exceed 250 Watts in the present example.

FIG. b schematically illustrates an Ethernet video surveillance system.The elements in common with the system of FIG. 1a have the samereferences and are not described again.

In the present example, the receivers 103 and 104 provide power to thecameras through Ethernet cables and are PoE enabled Ethernet switches.

One camera can be directly connected to one port of the Receiver, orseveral cameras can be connected to one port of the Receiver through anintermediate PoE pass-through switch (119, 120).

For example camera 110 is directly connected to “port 4” 107 of receiver103 while cameras 109 and 108 are connected to “port 2” of receiver 103through the intermediate PoE pass-through Ethernet switch 119.

PoE pass-through switches are configured to receive power from onededicated port and then to distribute the received power to theremaining ports. (Cisco Catalyst® 3560-C and 2960-C Series Switches areexamples of PoE pass-through switches).

The LAN infrastructure 102 includes switches, routers and gateways fortransporting the IP video to the VMS 101.

The VMS (“Video Monitoring System”) 101 displays the IP video streamsfor the surveillance purpose. Also the VMS 101 displays a user interfaceallowing the operator to configure the cameras, to change the cameraspower profile and to receive power alerts from the cameras (FIG. 2).

An example of Receiver is the Netgear® GS110TP smart switch.

With reference to FIG. 2, information that can be displayed and modifiedby the VMS 101 is described.

The “admin configuration screen” 200 is managed by the systemadministrator mainly during the system installation and configuration.The screen shows the parameters that a system administrator canconfigure for each camera. The parameters include:

-   -   Camera ID: an identification of the camera.    -   Group ID: an identification of the Receiver that provides the        power to the Camera. For example, according to FIGS. 1a and 1b ,        cameras 108, 109 and 110 shall be configured with group id set        to “Recevier1” while cameras 113, 112 and 111 have a group id        set to “Recevier2”.    -   Port ID: an identification of the Receiver port that provides        power to the camera. For example, according to FIGS. 1a and 1b        cameras 108 and 109 have a port id set to “2”, camera 110 has a        port id set to “4” and cameras 113, 112 and 111 have a port id        set to “3”.    -   Group max power: this parameter reflects the maximum power that        can be delivered by the Receiver that provides power to the        camera. For example, according to FIGS. 1a and 1b , all cameras        shall have the group max power set to 250 watt.    -   Port max power: this parameter reflects the maximum power that        can be delivered by the port of the receiver that provides power        to the camera. For example, according to FIGS. 1a and 1b , all        cameras shall have the group max power set to 75 watt.    -   Default power profile: this parameter defines the power profile        of the camera after a cycle power on. Four illustrative possible        profiles are described:        -   PTZ: the camera movements are allowed including the optical            zoom setup,        -   Hi_res: the camera can be set to the highest image            resolution, camera movements are not allowed,        -   Lo_res: the camera cannot be set to high resolution and the            camera movements are not allowed,        -   Sleep: the camera is not allowed to stream video and the            camera movement are not allowed,    -   Authorized power profiles: this parameter defines the power        profile that the administrator wants to authorise for the        camera. For example, if an administrator wants that the camera        never to be in sleep mode and it doesn't want to set a        particular resolution or the ability to move, then the        administrator sets (1,1,1,0) as the authorized power profiles        for the set of profiles (PTZ, Hi_res, Lo_res, Sleep), where “1”        indicates that the corresponding profile is authorized and “0”        indicates that the corresponding profile is not authorized.    -   Power consumption: this parameter defines the camera power        consumption in the different profiles:        -   P_PTZ: power consumed by the camera when in PTZ profile,        -   P_HI_res: power consumed by the camera when in Hi_res            profile,        -   P_Lo_res: power consumed by the camera when in Lo_res            profile,        -   P_Sleep: power consumed by the camera when in Sleep profile.

When the system administrator sets or changes a camera configuration,then the VMS sends an “Admin update” message (561, see FIG. 5a ) to thecamera.

The “operator camera control” screen 201 is used by the VMS operatorduring the system operation. This screen enables the operator todynamically manage the camera power profiles. For example, duringoperation, the operator might want to increase the resolution of oneparticular camera, or change the angle of view or wakeup a sleepingcamera. To do so, the operator goes to the “operator camera controlscreen” 201, checks whether the camera is in the appropriate powerprofile corresponding to the desired modification, and if necessary,changes the camera power profile and/or authorized power profile.

When the operator changes the camera power profile in screen 201, achange PP (acronym for “power profile”) message (531, see FIG. 5a ) issent by the VMS 101 to the camera to instruct it to change the powerprofile. Then, the camera might negotiate with other cameras a share inthe global power budget. When the camera power profile change issuccessful, then the camera sends a positive CPP acknowledgement(acronym for “change power profile”) message (551, see FIG. 5a ) to theVMS 101 and the new camera power profile is displayed in screen 201. Ifthe camera failed to change the power profile, then the camera sends anegative CPP acknowledgement message (531, see FIG. 5a ) to VMS 101,screen 201 still displays the old camera power profile and an errorscreen 202 or 203 pops up.

Error screen 202 indicates that camera X cannot change its power profilebecause port Y of receiver Z cannot provide enough power for thatprofile.

Error screen 203 indicates that camera X cannot change its power profilebecause receiver Z cannot provide enough power for that profile.

System alert screens can popup mainly at system start up. These alertsare provided for detecting a system misconfiguration. If the systemadministrator failed to configure the camera default power profiles tomatch the receivers capacity. Alert messages (571, see FIG. 5a ) aresent by the cameras at start up. VMS 101 pops up the system error screen204 if a receiver port does not have the capacity to power the cameraswith their respective power profiles, or the system error screen 205 ifa receiver does not have the global power capacity for all ports.

Cameras according to embodiments are described in what follows withreference to FIGS. 3, 3 a, 3 b and 3 c.

FIG. 3 illustrates three different embodiments of this invention. A coaxcamera 1501, an IP camera 1502 and a modular coax camera 1505 arerepresented.

The coax camera 1501 is a network surveillance camera with integrated IPover Coax interface. An example is represented by FIG. 3 a.

The IP camera 1502 is a network surveillance camera. An embodiment of anIP camera is illustrated by FIG. 3 b.

The modular IP over coax camera 1505 comprises an IP camera 1502connected by an Ethernet cable 1504 to a coax over IP adapter 1503. Themodular IP coax camera according to an embodiment is represented by FIG.3 c.

FIG. 3a illustrates a coax camera 1501 according to an embodiment. Forthe sake of conciseness, the following description focuses mainly on therelevant parts of the camera which has been represented in a simplifiedfashion.

A core camera unit 301 is represented that includes the large part ofthe camera functions such as the optics, the sensor, the video processorand the RTP/IP video server.

An EoC unit 303 includes the functions of Ethernet transport overcoaxial cable and power management. This unit is used for IP over coax(such as in FIG. 1a ). For Ethernet camera (such as in FIG. 1b ) the EoCunit 303 is not used.

A RJ45 port (not represented by the FIGS.) may be used if the camera ispart of an Ethernet system (such as in FIG. 1b ).

The BNC port 307 is used for IP communication over coax cable (such asin FIG. 1a ).

The CPU 304 manages the power profile in accordance with the powerbudget in the camera. It gets power parameters from the non-volatilememory nvRAM 313 when it is powered, it exchanges messages with the VMS101 and other cameras through the Ethernet bridge 312. The powerparameters are kept in the RAM 314 during run time.

The camera gets its power from the BNC port 307 (coax system, such as inFIG. 1a ).

According to another embodiment (not represented by the FIGS.), thecamera may get its power from a RJ45 port (Ethernet system, such as inFIG. 1b ).

The HomePlug AV bridge 303 is configured to encapsulate the core CameraIP traffic into HomePlug AV packets and to send them on the Coax cablethrough the BNC port 307. The HomePlug AV bridge 303 is also configuredto extract IP traffic from the received HomePlug AV packets and toforward this IP traffic to the Camera Core Unit.

The Ethernet bridge 312 is configured to mix IP traffics from theHomePlug AV bridge 303 and the Core Camera Unit.

An example of HomePlug AV bridge is the Devolo® dLAN 200 AVmodule(INT6400).

The flowcharts described below with reference to FIGS. 6, 7, 8 and 13are executed by the CPU 304. This embodiment is particularlyadvantageous for IP over Coax systems since the camera is integratedthus generating cost saving for maintenance and installation.

FIG. 3b illustrates an IP camera according to an embodiment of theinvention. In order to keep the readability of the diagram and to focusmainly on the invention the diagram of the camera has been simplified.The camera 1502, the optics, the sensor, the video processor and theRTP/IP video server are here after described in a simplified manner.

The camera 1502 comprises a lens 325, a sensor such as a Cmos sensor324, a video processor 323, a network processor 322, a non-volatilememory 321 and a RAM memory 326, both associated to the networkprocessor 322. The camera gets power from the Ethernet port 309 by a PoEPD (“Powered device”) module 327.

The flowcharts described below with reference to FIGS. 6, 7, 8 and 13are executed by the network processor 322. This embodiment isparticularly advantageous since it can be applied in standard Ethernetsystems.

FIG. 3c illustrates a modular coax camera 1505 according to anembodiment of the invention. In order to keep the readability of thediagram and to focus mainly on the invention the diagram of the camerahas been simplified.

As described with reference to FIG. 3, the modular IP over coax camera1505 comprises an IP camera 1502 connected by an Ethernet cable 1504 toa coax over IP adapter 1503.

The IP camera unit 1502 includes the large part of the camera functionsincluding the optics, the sensor, the video processor and the RTP/IPvideo server but it here after described in a simplified manner.

The IP over coax adapter unit 1503 includes the functions of Ethernettransport over coaxial cable and of power from coaxial cable.

The method of managing power according to the invention is mainlyimplemented in the CPU 304 (MICA “Modular IP over coax-adapter focus”)or in the network processor 322 (MICC “Modular IP over coax—camerafocus”).

A BNC port 307 is used for IP communication over coax cable.

A CPU 304 manages for example the core camera start and stop and theelection of a Master camera. The CPU 304 stores the power change record410 in the NVRAM 313. It exchanges messages with other cameras throughthe Ethernet bridge 312.

The camera gets its power from the BNC port 307. The power is directedthrough the line 317 to both the subsystem DC/DC converter 319 and thePoE PSE (“Power Sourcing Equipment”) module 316. The DC/DC converter 319is responsible to provide power to the IP over coax adapter, mainly thecommunication subsystem (312, 303, 304, 314, 313, 316, 319). The PoE PSEmodule 316 is responsible to provide power to the IP camera unit 1502.The PoE PSE module 316 is controlled by the CPU 304 through the signal318. By acting on the signal 318, the CPU 304 will control the power tobe delivered to IP camera 1502.

The HomePlug AV bridge 303 is responsible for encapsulating the coreCamera IP traffic into HomePlug AV packets and to send them on thecoaxial cable through the BNC port 307. The HomePlug AV bridge 303 isalso responsible to extract IP traffic from the received HomePlug AVpackets and to forward this IP traffic to the IP Camera unit 1502.

The Ethernet bridge 312 is responsible for mixing IP traffics from theHomePlug AV bridge 303 and the IP camera unit 1502.

An example of HomePlug AV bridge is the dLAN 200 AVmodule (INT6400) fromDevolo.

The IP camera unit 301 is composed of a lens 325, a sensor such as aCmos sensor 324 a video processor 323, a network processor 322 and anon-volatile memory 321 and a RAM memory 326, both associated to thenetwork processor 322.

The MICA modular IP over Coax embodiment system target is described inFIG. 1a . The method of managing power according to the invention ismainly implemented in a modular IP over Coax camera 1505 and moreprecisely in the IP over Coax adapter 1503. In particular, theflowcharts of FIGS. 6, 6 a, 7, 8 and 13 are executed by the CPU 304.This embodiment is particularly advantageous for IP over Coax systemssince it offers the flexibility of choosing separately the camera andthe adapter.

The MICC modular IP over Coax embodiment system target is described inFIG. 1a . The method of managing power according to the invention ismainly is implemented in a modular IP over Coax camera 1505 and moreprecisely in the IP camera 1502. In particular, the flowcharts of FIGS.6, 6 b 7, 8 and 13 are executed by the network processor 322. Thisembodiment is particularly advantageous for IP over Coax systems sinceit offers the flexibility of choosing separately the camera and theadapter like the MICA, and additionally it has the advantage of moreprecise power consumption calculations thanks to the power consumptionvalues exchanged between the IP camera and the IP over Coax adapter.

The data processed by the camera CPU 304 (FIG. 3a ), the adapter CPU 304(FIG. 3c ) and the network processor 322 (FIG. 3b ) is described in whatfollows with reference to FIG. 4 a.

Depending on the camera embodiment, the power parameters are stored inthe non-volatile memory 313 (FIGS. 3a and 3c ) or in the non-volatilememory 321 (FIG. 3b ). These parameters may be default factoryparameters that can be overwritten by the camera during operation wheninstructed by the VMS 101 upon request of the administrator for changeof the values of the “admin configuration” screen 200.

The nvRAM 313 parameters include:

-   -   Camera ID (401): an identification of the camera    -   Group ID (402): an identification of the Receiver that provides        the power to the Camera. For example, according to FIGS. 1a and        1b , cameras 108, 109 and 110 shall be configured with group id        set to “Recevier1” while cameras 113, 112 and 111 have a group        id set to “Recevier2”.    -   Port ID (403): an identification of the receiver port that        provides power to the camera. For example, according to FIGS. 1a        and 1b , cameras 108 and 109 have a port id set to “2”, camera        110 has a port id set to “4” and cameras 113, 112 and 111 have a        port id set to “3”.    -   Group max power (404): this parameter reflects the maximum power        that can be delivered by the receiver that provides power to the        camera. For example, according to FIGS. 1a and 1b , all cameras        shall have the group max power set to 250 watt.    -   Port max power (405): this parameter reflects the maximum power        that can be delivered by the port of the receiver that provides        power to the camera. For example, according to FIGS. 1a and 1b ,        all cameras shall have the group max power set to 75 watt.    -   Default power profile (406): this parameter defines the power        profile of the camera after a cycle power on. Four illustrative        possible profiles are described:        -   PTZ: the camera movements are allowed including the optical            zoom setup,        -   Hi_res: the camera can be set to the highest image            resolution, camera movements are not allowed,        -   Lo_res: the camera cannot be set to high resolution and the            camera movements are not allowed,        -   Sleep: the mare is not allowed to stream video and the            camera movement are not allowed,    -   Authorized power profiles (407): this parameter defines the        power profile that the administrator wants to authorise for the        camera. For example, if an administrator wants the camera never        to be in sleep mode and if resolution and the ability to move        are not of importance, then the administrator sets (1,1,1,0) as        the authorized power profiles for the set of profiles (PTZ,        Hi_res, Lo_res, Sleep), where “1” indicates that the        corresponding profile is authorized and “0” indicates that the        corresponding profile is not authorized.    -   Power consumption (408): this parameter defines the camera power        consumption in the different profiles:        -   P_PTZ: power consumed by the camera when in PTZ profile,        -   P_HI_res: power consumed by the camera when in Hi_res            profile,        -   P_Lo_res: power consumed by the camera when in Lo_res            profile,        -   P_Sleep: power consumed by the camera when in Sleep profile.

During run time camera CPU 304 or adapter CPU 304 (FIGS. 3a and 3c )manages the available power budget and its own power profile bymaintaining a data structure in the RAM 314. According to the cameraembodiment represented by FIG. 3b , during run time network processor322 manages the available power budget and its own power profile bymaintaining a data structure in the RAM 326.

This data structure comprises one or more Group objects 410 containing:

-   -   The group ID as set in the Group ID parameter 402,    -   The total group power consumed: the sum of the power profiles of        all the camera connected to the Receiver,    -   Pointer to port objects: each port of the Receiver is        represented by a port object 411,

The port object 411 contains:

-   -   The port ID as set in the port ID parameter 403,    -   The total port power consumed: the sum of the power profiles of        all the camera connected to the Receiver port,    -   Pointer to camera object: each camera is represented by a camera        object 412,

The camera object 412 contains:

-   -   The camera ID: local id as set in the Camera ID parameter 401 or        id of the other cameras as the CPU is receiving “Network join”        messages (501, see FIG. 5a ) or “PP info” message (521, see FIG.        5a ),    -   The Power profile: as set in the default power profile parameter        406, or as modified by the VMS (“Change PP” message 531, see        FIG. 5a ) if local camera or as set in “Network join” messages        (501, see FIG. 5a ) or “PP info” message (521, see FIG. 5a )        from other camera,    -   Authorized power profile: as set in the “authorized power        profiles” parameter 407 or as modified by VMS (“Change APP”        message 551, see FIG. 5a ) if local camera, or as set in        “Network join” messages (501, see FIG. 5a ) from other camera,    -   Power consumption information as set in the “power consumption”        parameter 408.

FIG. 4b illustrates the data stored in the IP over Coax adapter NVRAM313 for power consumption. The data structure 1801 reflects the powerconsumption of the IP over Coax adapter 1503. It is initialized eitherin factory or as a maintenance or installation process. If the powerconsumption of the 1503 is constant then all the fields 1806, 1807,1808, and 1809 are set to the same value of power consumption. If theadapter manufacturer notices a significant difference in powerconsumption of the adapter 1503 when the associated camera is indifferent known states then:

The field 1806 represents the power consumed by the IP over Coax adapter1503 when the camera is in sleep mode

The field 1807 represents the power consumed by the IP over Coax adapter1503 when the camera is in low resolution mode

The field 1808 represents the power consumed by the IP over Coax adapter1503 when the camera is in high resolution mode

The field 1809 represents the power consumed by the IP over Coax adapter1503 when the camera is in PTZ mode

The messages exchanged between the cameras and the VMS are describedwith reference to FIG. 5 a.

Upon initialization of the system (upon start-up or powering-up), eachcamera sends a “network join” message 501. This message is sent inbroadcast mode so that every camera and the VMS can receive it. Themessage contains the “group id” 502, the “port id” 503, the “camera id”504, the “power profile” 505 and the “authorized power profile” 506 ofthe sending camera.

When a camera changes its power profile, it broadcasts a “PP update”message 511 to all other cameras. The message contains the “group id”512, the “port id” 513, the “camera id” 514 and the new “power profile”515 of the sending camera.

When a camera detects a new camera in the system, it sends its own powerprofile to the new camera by sending a “PP info” message 521. Themassage contains the “group id” 522, the “port id” 523, the “camera id”524 and the “power profile” 525 of the sending camera.

When the VMS operator changes the power profile of a camera throughscreen 201, the VMS sends a “change PP” message 531 to that camera.Also, when a remote camera wants to change the power profile of anothercamera, the remote camera sends a “change PP” message 531 to thatcamera. The message contains the new “power profile” 532.

When the VMS operator changes the “authorized power profile” of a camerathrough screen 201, the VMS sends a “change APP” message 541 to thatcamera. The message contains the new “authorized power profile” 542.

When a camera completed the change of its own power profile, uponrequest of the VMS or upon request of another camera, it sends back a“CPP ack” message 551 to the requesting device (VMS or camera) toindicate the status of the change attempt (OK when the change attempthas succeeded, KO PORT when the change has not succeeded because of theport, KO RECEIVER when the change has not succeeded because of thereceiver). The massage contains a “status” field 552.

When an administrator changes the camera configuration through the VMSscreen 200, the VMS sends an “admin update” message 561 to the camera.The message contains the “camera id” 562, the “group id” 563, the “portid” 564, the “group maximum power” 565 the “port maximum power” 567, the“default power profile” 567, the “authorized power profile” 568, the“camera power consumption” for each power profile 569.

When a camera detects a situation where the receiver will not be able tohandle all the cameras with their respective power profiles, its sendsan “alert” message 571 to the VMS. The message contains the “group id”572 and “port id” 573 of the receiver to which the camera is connected,the “camera id” 574 and a “status” 575:

-   -   RECEIVER: The receiver port can handle the cameras, but the        total power capacity of the receiver is reached,    -   PORT: The receiver port cannot handle the cameras.

FIG. 5b illustrates the messages that may be exchanged between the IPcamera 1503 and the IP over Coax adapter 1502. The message “switch topower profile” 1830 is sent by the adapter CPU 304 of the IP over Coaxadapter 1502 (MICA implementation) to the network of the attached IPcamera 1503. The format of the message can be, and is not restricted to,an Ethernet frame compliant to the SNMP protocol, or any other levelprotocols that uses Ethernet packets. Of course it can be also a packetconformant to the IP (TCP or UDP or higher).

The field “power profile” 1831 contains a new power profile for the IPcamera 1503. When receiving the message the network processor 322 mustset the camera 1503 to the power profile as indicated in the field 1831.

The message “get module power consumption” 1801 is sent by the networkprocessor 322 of an IP camera to the CPU 304 of the locally attached IPover coax adapter 1502 (MICC implementation). The format of the messagecan be, and is not restricted to, an Ethernet frame compliant to theSNMP protocol, or any other level protocols that uses Ethernet packets.Of course it can be also a packet conformant to the IP (TCP or UDP orhigher).

Upon reception of a “Get module power consumption” message 1801, theadapter CPU 304 must respond with a “Module power consumption response”message 1810.

This “Module power consumption response” message 1810 contains:

-   -   A field 1811 which contains the power consumed by the IP over        Coax adapter 1503 when the camera is in sleep mode and is set to        NVRAM field 1806 (see FIG. 4b ),    -   A field 1812 which contains the power consumed by the IP over        Coax adapter 1503 when the camera is in low resolution mode and        is set to NVRAM field 1807,    -   A field 1813 which contains the power consumed by the IP over        Coax adapter 1503 when the camera is in high resolution mode and        is set to NVRAM field 1808, and    -   A field 1814 which contains the power consumed by the IP over        Coax adapter 1503 when the camera is in PTZ mode and is set to        NVRAM 1809 field.

The format of the message can be, and is not restricted to, an Ethernetframe compliant to the SNMP protocol, or any other level protocols thatuses Ethernet packets. Of course it can be also a packet conformant tothe IP (TCP or UDP or higher).

Power budget management according to embodiments is described in whatfollows with reference to FIG. 6 which is a flowchart of exemplary stepsexecuted by the camera CPU 304 or the adapter CPU 304 when powered.

In particular, the steps of the flowchart are executed by the camera CPU304 for the camera embodiments represented by FIG. 3a , and by theadapter CPU 304 for some embodiments represented by FIG. 3c . When,depending on the camera embodiment, the camera CPU or the adapter CPU ispowered, it executes all necessary actions during the boot phase 601 inorder to be ready for the run time. These actions include theinitialization of the peripherals such as the RAM 314, the nvRAM 313 andthe communication link 310 of the camera or the adapter respectively.

In order to make easier the reading of the description below concerningthe flowchart, the camera CPU 304, the adapter CPU 304 are named CPU.Camera elements such RAM, nvRAM may be elements of the camera (forembodiments represented by FIG. 3a ) or of the adapter (for embodimentsrepresented by FIG. 3c ) depending on the implemented embodiment.

Concerning camera embodiments represented by FIG. 3a (steps flowchartexecuted by the camera CPU 304), during the RAM initialization, the CPUcreates the group object 410 set with a group identification read fromnvRAM group ID 402. The total group power consumed is set to the cameradefault power profile obtained from nvRAM 406. Next, the CPU creates aport object 411 with a port identification read from nvRAM 403 and thesame power consumed as the group object. The CPU also creates a cameraobject set with the camera identification 401, power profile 406 andauthorized power profile 407 read from nvRAM. The CPU then links thethree objects, first from group to port and then from port to camera. Inother words, the CPU sets the group object pointer to point to the portobject and then the CPU sets the port object pointer to point to thecamera object.

Concerning camera embodiments represented by FIG. 3c in which stepsflowchart are executed by the adapter CPU 304, the boot phase 601comprises several supplementary steps concerning the communication ofthe network processor 322 and the adapter CPU 304 for camera powerprofile initialization.

FIG. 6a illustrates the boot phase 601 for these embodiments, inparticular it illustrates the communication of the network processor 322and the CPU 304 for camera power profile initialization.

When the adapter CPU 304 is powered, it executes all necessary actionsduring the boot phase 601 in order to be ready for the run time. Theseactions include the initialization of the peripherals such as the RAM304, the nvRAM 313 and the communication link 309. During the step 2001the CPU creates the group object 410 initialized with a groupidentification read from nvRAM group ID 402. The total group powerconsumed is initialized to the power consumption of camera in itsdefault power profile. The default power profile is obtained from nvRAM406 and the power consumed is obtained from NVRAM 408. Next during thestep 2004 the CPU sends a “switch to power profile” message 1830 withthe field “power profile” 1831 set to the camera default power profileobtained from nvRAM 406. Next during the step 2003, the CPU creates aport object 411 with a port identification read from nvRAM 403 and thesame power consumed as the group object. Next during the step 2004 theCPU also creates a camera object set with the camera identification 401,power profile 406 and authorized power profile 407 read from nvRAM. TheCPU then links the three objects, first from group to port and then fromport to camera. In other words, the CPU sets the group object pointer topoint to the port object and then the CPU sets the port object pointerto point to the camera object.

Returning to FIG. 6, during a next step 602, the CPU sends a networkjoin message 501 so that each camera connected to the system includesthe power profile of the newly powered camera into the budgetcalculation. The message is set as follows:

-   -   The message field group id 502 is set with the identification of        the RAM group object 410,    -   The message field port id 503 is set with the identification of        the RAM port object 411,    -   The message field camera id 504 is set with the identification        of the RAM camera object 412,    -   The message field power profile 505 is set with the power        profile of the RAM camera object 412,    -   The message field authorized power profile 506 is set with the        authorized power profile of the RAM camera object 412,

Next, during a step 603, the CPU 304 waits for the reception of amessage from remote cameras or from the VMS.

When the CPU receives a change PP message 531, it executes step 604. Thechange PP message can be sent either by the VMS as part of an operatoraction in screen 201. It can also be sent by a remote camera as part ofa power budget negotiation.

During step 604 the CPU checks if the new power profile would increasethe camera power consumption or not (like for example if the camerapower profile is “low resolution” and the new power profile is “highresolution”).

If the camera power consumption is unchanged or decreased, then, duringstep 606, the CPU updates the camera power profile with the new value inthe camera object 412 in RAM.

Then, concerning embodiments represented in FIG. 3a in which theflowchart is executed by the camera CPU 304, the CPU updates the Totalport power consumed in the port object 411 by subtracting from the totalthe difference of power consumption of the camera according to the oldand new power profiles. The CPU then also updates the Total group powerconsumed in the group object 410 by subtracting from the total thedifference of power consumed of the port according to the old and newpower consumed.

Concerning embodiments represented in FIG. 3c in which the flowchart isexecuted by the adapter CPU 304, the CPU sends a “switch to powerprofile” message 1830 to the camera with the field “power profile” 1831set to the new power profile. Then, the CPU updates the Total port powerconsumed in the port object 411 by subtracting from the total thedifference of power consumption of the camera according to the old andnew power profiles. The CPU then also updates the Total group powerconsumed in the group object 410 by subtracting from the total thedifference of power consumed of the port according to the old and newpower consumed.

Then, during a step 607, the CPU returns a CPP acknowledgement message551 to the sender with the status field 552 set to OK.

During step 608, the CPU sends a PP update broadcast message 511 toadvertise all other devices about the camera new power profile. Themessage is set as follows:

-   -   The message field group id 512 is set with the identification of        the RAM group object 410,    -   The message field port id 513 is set with the identification of        the RAM port object 411,    -   The message field camera id 514 is set with the identification        of the RAM camera object 412,    -   The message field power profile 515 is set with the power        profile of the RAM camera object 412,

Then, the CPU loops back to step 603 for the reception of further othermessages.

If the camera power consumption is increased, then, during step 605 theCPU negotiates an increase of the camera power consumption in thesystem. This step is described in details with reference to FIG. 7. Itcomprises a new power consumed calculation and if the power consumedwould exceed the Receiver or port capacity, then the CPU sends messagesto remote cameras in order to instruct them to lower their powerprofiles. Then, the CPU loops back to step 603 for the reception ofother messages.

When the CPU receives a PP update message 511 from a remote camera, thenit executes step 609. A PP update message is sent by a remote camera incase the remote camera has changed its power profile upon request fromthe VMS or upon request of another camera.

Before sending such notification the remote camera checks whether thepower capacity of the system will not be exceeded after switching to thenew power profile.

During step 609, the CPU compares the group id 512 of the remote camerawith the group id of the group object 410. If it matches, then the CPUupdates the power profile information in the camera object 412corresponding to both the remote camera id 514 and port id 513. For thispurpose, the power profile info 515 is used.

Next, the CPU updates the port total power consumed and the group totalpower consumed. The CPU then loops back to step 603 for the reception ofother messages.

When the CPU receives a network join message 501 from a newly poweredcamera, then it executes step 610.

During step 610 the CPU compares the group id 502 of the remote camerawith the group id of the group object 410. If it matches, then the CPUcreates a new camera object 412 corresponding to both the remote cameraid 504 and port id 503. For this purpose, the power profile info 505 isused. Next, the CPU updates the port total power consumed and the grouptotal power consumed. The power budget bounds are not checked at thisstep and this is left to the newly powered camera.

Next, during step 611, the CPU sends back to the newly powered camera aPP info message 521. The message is set as follows:

-   -   The message field group id 522 is set with the identification of        the RAM group object 410,    -   The message field port id 523 is set with the identification of        the RAM port object 411,    -   The message field camera id 524 is set with the identification        of the RAM camera object 412,    -   The message field power profile 525 is set with the power        profile of the RAM camera object 412.

Then, the CPU loops back to step 603 for the reception of othermessages.

When the CPU receives a PP info message 521 from a remote camera, itexecutes step 612. The PP info messages 521 are sent back to the cameraas a result of the reception of a network join message 501 sent by thecamera when it is powered.

During step 612 the CPU creates a camera object 412 corresponding to theremote camera that sent the PP info message. The camera object is linkedto a port object 411 if it already exists. Otherwise, it is linked to anewly created port object 411. A receiver object 410 can also be newlycreated if needed.

During step 613, the CPU integrates the remote camera power profile intothe power consumption calculation. Then, it might take actions in orderto modify its own power profile if an overflow is detected. This step isdescribed in details with reference to FIG. 8. Then, the CPU loops backto step 603 for reception of other messages.

When the CPU receives an admin update message 561 from the VMS isexecutes step 614.

During step 614 the CPU updates the nvRam parameters as follows:

-   -   The message field camera id 562 is written in the nvRAM camera        id field 401,    -   The message field group id 563 is written in the nvRAM group id        field 402,    -   The message field port id 564 is written is written in the nvRAM        port id field 403,    -   The message field group maximum power 565 is written in the        nvRAM group maximum power field 404,    -   The message field port maximum power 566 is written in the nvRAM        port maximum power field 405,    -   The message field default power profile 567 is written in the        nvRAM default power profile field 406,    -   The message field authorized power profile 568 is written in the        nvRAM authorized power profile field 407,    -   The message field power consumption 569 is written in the nvRAM        Power consumption field 408.

Then, the CPU loops back to step 603 for the reception of othermessages.

In embodiments represented by FIG. 3b and in some embodimentsrepresented by FIG. 3c , the method of managing power according to theinvention, and in particular the flowchart steps represented by FIG. 6are executed by the network processor 322.

When the network processor 322 is powered, it executes all necessaryactions during the boot phase 601 in order to be ready for the run time.These actions include the initialization of the peripherals such as theRAM 326, the nvRAM 321 and the communication link 309.

FIG. 6b illustrates the communication of the network processor 322 andthe CPU 304 for IP over coax adapter power consumption initialization(step 601 of FIG. 6)

During a step 2101 the network processor sends a “get module powerconsumption” message 1801 to the adapter CPU 304. Then during a step2102 the network processor receives the “module power consumptionresponse” message 1810 from the CPU.

Next during a step 2103 the Network processor updates the cameraconsumption information 408 in the Nvram 321. Each field is increased bythe corresponding field of the “module power consumption response”message 1810.

During a step 2104 the network processor creates the group object 410initialized with a group identification read from nvRAM group ID 402.The total group power consumed is initialized to the power consumptionof camera in its default power profile. The default power profile isobtained from nvRAM 406 and the power consumed is obtained from NVRAM408. Next during the step 2104, the network processor creates a portobject 411 with a port identification read from nvRAM 403 and the samepower consumed as the group object.

Next during the a 2105 the network processor also creates a cameraobject set with the camera identification 401, power profile 406 andauthorized power profile 407 read from nvRAM. The network processor thenlinks the three objects, first from group to port and then from port tocamera. In other words, the network processor sets the group objectpointer to point to the port object and then the network processor setsthe port object pointer to point to the camera object.

Returning to FIG. 6, during a next step 602, the NETWORK PROCESSOR sendsa network join message 501 so that each camera connected to the systemincludes the power profile of the newly powered camera into the budgetcalculation. The message is set as follows:

The message field group id 502 is set with the identification of the RAMgroup object 410,

-   -   The message field port id 503 is set with the identification of        the RAM port object 411,    -   The message field camera id 504 is set with the identification        of the RAM camera object 412,    -   The message field power profile 505 is set with the power        profile of the RAM camera object 412,    -   The message field authorized power profile 506 is set with the        authorized power profile of the RAM camera object 412.

Next, during a step 603, the network processor is waits for thereception of a message from remote cameras or from the VMS.

When the network processor receives a change PP message 531, it executesstep 604. The change PP message can be sent either by the VMS as part ofan operator action in screen 201. It can also be sent by a remote cameraas part of a power budget negotiation.

During step 604 the network processor checks if the new power profilewould increase the camera power consumption or not (like for example ifthe camera power profile is “low resolution” and the new power profileis “high resolution”).

If the camera power consumption is unchanged or decreased, then, duringstep 606, the network processor updates the camera power profile withthe new value in the camera object 412 in RAM.

Then, the network processor updates the Total port power consumed in theport object 411 by subtracting from the total the difference of powerconsumption of the camera according to the old and new power profiles.The network processor then also updates the Total group power consumedin the group object 410 by subtracting from the total the difference ofpower consumed of the port according to the old and new power consumed.

Then, during a step 607, the network processor returns a CPPacknowledgement message 551 to the sender with the status field 552 setto OK.

During step 608, the network processor sends a PP update broadcastmessage 511 to advertise all other devices about the camera new powerprofile. The message is set as follows:

-   -   The message field group id 512 is set with the identification of        the RAM group object 410,    -   The message field port id 513 is set with the identification of        the RAM port object 411,    -   The message field camera id 514 is set with the identification        of the RAM camera object 412,    -   The message field power profile 515 is set with the power        profile of the RAM camera object 412.

Then, the network processor loops back to step 603 for the reception offurther other messages.

If the camera power consumption is increased, then, during step 605 thenetwork processor negotiates an increase of the camera power consumptionin the system. This step is described in details with reference to FIG.7. It comprises a new power consumed calculation and if the powerconsumed would exceed the Receiver or port capacity, then the networkprocessor sends messages to remote cameras in order to instruct them tolower their power profiles. Then, the network processor loops back tostep 603 for the reception of other messages.

When the network processor receives a PP update message 511 from aremote camera, then it executes step 609. A PP update message is sent bya remote camera in case the remote camera has changed its power profileupon request from the VMS or upon request of another camera.

Before sending such notification the remote camera checks whether thepower capacity of the system will not be exceeded after switching to thenew power profile.

During step 609, the network processor compares the group id 512 of theremote camera with the group id of the group object 410. if it matches,then the network processor updates the power profile information in thecamera object 412 corresponding to both the remote camera id 514 andport id 513. for this purpose, the power profile info 515 is used.

Next, the network processor updates the port total power consumed andthe group total power consumed. The network processor then loops back tostep 603 for the reception of other messages.

When the network processor receives a network join message 501 from anewly powered camera, then it executes step 610.

During step 610 the network processor compares the group id 502 of theremote camera with the group id of the group object 410. if it matches,then the network processor creates a new camera object 412 correspondingto both the remote camera id 504 and port id 503. for this purpose, thepower profile info 505 is used. Next, the network processor updates theport total power consumed and the group total power consumed. The powerbudget bounds are not checked at this step and this is left to the newlypowered camera.

Next, during step 611, the network processor sends back to the newlypowered camera a PP info message 521. The message is set as follows:

-   -   The message field group id 522 is set with the identification of        the RAM group object 410,    -   The message field port id 523 is set with the identification of        the RAM port object 411,    -   The message field camera id 524 is set with the identification        of the RAM camera object 412,    -   The message field power profile 525 is set with the power        profile of the RAM camera object 412.

Then, the network processor loops back to step 603 for the reception ofother messages.

When the network processor receives a PP info message 521 from a remotecamera, it executes step 612. The PP info messages 521 are sent back tothe camera as a result of the reception of a network join message 501sent by the camera when it is powered.

During step 612 the network processor creates a camera object 412corresponding to the remote camera that sent the PP info message. Thecamera object is linked to a port object 411 if it already exists.Otherwise, it is linked to a newly created port object 411. A receiverobject 410 can also be newly created if needed.

During step 613, the network processor integrates the remote camerapower profile into the power consumption calculation. Then, it mighttake actions in order to modify its own power profile if an overflow isdetected. This step is described in details with reference to FIG. 8.Then, the network processor loops back to step 603 for reception ofother messages.

When the network processor receives an admin update message 561 from theVMS is executes step 614.

During step 614 the network processor updates the nvRam parameters asfollows:

-   -   The message field camera id 562 is written in the nvRAM camera        id field 401,    -   The message field group id 563 is written in the nvRAM group id        field 402,    -   The message field port id 564 is written is written in the nvRAM        port id field 403,    -   The message field group maximum power 565 is written in the        nvRAM group maximum power field 404,    -   The message field port maximum power 566 is written in the nvRAM        port maximum power field 405,    -   The message field default power profile 567 is written in the        nvRAM default power profile field 406,    -   The message field authorized power profile 568 is written in the        nvRAM authorized power profile field 407,    -   The message field power consumption 569 is written in the nvRAM        Power consumption field 408.

Then, the network processor loops back to step 603 for the reception ofother messages.

In what follows, power budget calculation and power negotiation withother cameras is described with reference to FIG. 7 which is a flowchartof exemplary steps executed by the camera CPU, the adapter CPU or thenetwork processor depending on the implemented embodiments.

In order to make easier the reading of the description below concerningthe flowchart, CPU may mean the camera CPU 304, the adapter CPU 304 orthe network processor 322 depending on the implemented embodiment. In asimilar manner, camera elements such RAM, nvRAM may be elements of thecamera (for embodiments represented by FIGS. 3a, 3b and some embodimentsrepresented by FIG. 3c ) or of the adapter (for some embodimentsrepresented by FIG. 3c ) depending on the implemented embodiment.

Power budget calculation and power negotiation with other camerascorresponds to step 605 in FIG. 6.

First, during step 701, the CPU (or network processor) calculates thenew total power consumed by the receiver port taking into account thenew power profile wanted for the camera. For this purpose, it adds thedifference of power consumed by the camera according to the currentpower profile and according to the new power profile to the field “Totalport power consumed” of the port object 411.

During test 702, the CPU (or network processor) compares the newcalculated port power consumption with the port maximum power capacity405.

If the port maximum power capacity is exceeded, then, step 703 isexecuted. During step 703, the CPU gets a camera object 412 of a remotecamera from the list of camera objects linked to the port object 411.

Then, during step 704 the CPU (or network processor) gets from thecamera object the power profile and the authorized power profiles of theremote camera. The CPU (or network processor) checks whether it ispossible to lower the remote camera power profile (the remote camera isnot in sleep mode and lower power profiles are allowed).

Two strategies may be implemented. According to a first strategy, thepower profile of the cameras is lowered to the minimum until acceptabletotal power consumption is reached. According to a second strategy, thepower profile is changed on an incremental basis per camera in arecurring manner until acceptable total power consumption is reached,for example, the increment is a minimum change of the power profile.

If the remote camera power profile cannot be lowered, then, during step708, the CPU (or network processor) checks whether this was the lastremote camera from the list of remote cameras attached to the receiverport that might have its power profile lowered.

According to the above first strategy, each camera is tested once,whereas according to the second strategy, each camera can be testedseveral times.

In case there are no more candidate cameras for power profile lowering,then, during step 709 the CPU (or network processor) returns a negativeacknowledgement to the sending device (VMS or camera) indicating theimpossibility of changing its own power profile because the receiverport power capacity does not allow it (CPP acknowledgement message 551with status 552 set to KO_PORT). This step ends the power negotiationprocedure.

If there remain cameras that might change their power profile, then, theCPU (or network processor) loops back to step 703 to select a new remotecamera.

Back to test 704, if the remote camera power profile can be lowered,then, during step 705, the CPU (or network processor) sends a change PPmessage 531 to the remote camera with the PP field 532 set to the lowestauthorized power profile (when the first strategy is implemented) or thenext lowest authorized power profile (when the second strategy isimplemented).

A third strategy may be implemented wherein the CPU (or networkprocessor) broadcasts the change PP message 531 to all known cameras,thereby avoiding process of selecting the cameras. However, according tothis strategy, the power consumption decrease may be more drastic thanactually needed if several cameras reduce their consumptionsimultaneously.

Then, during step 706 the CPU (or network processor) waits for anacknowledgment from the remote camera. If no acknowledgement isreceived, then the CPU loops back to step 703.

If an acknowledgement is received from the remote camera (CPPacknowledgement 551) with the status 552 OK, then, during step 707, theCPU (or network processor) updates the power profile information of theremote camera in the corresponding camera object 412. Next, the CPU (ornetwork processor) loops back to step 701 to update the total port powerconsumed.

Back to test 702, if the port maximum power capacity has not beenreached, then the CPU (or network processor) calculates, during step710, the receiver total power consumed by taking into account the cameranew requested power profile. For this purpose, it adds the difference ofpower consumed by the camera according to the current power profile andaccording to the new power profile to the field “Total group powerconsumed” of the port object 410.

During test 711, the CPU (or network processor) compares the newcalculated receiver power consumed with the receiver maximum powercapacity 404.

If the receiver maximum power capacity is exceeded, then step 712 isexecuted. During step 712 the CPU (or network processor) gets a cameraobject 412 of a remote camera from the list of camera objects linked tothe receiver object 410.

Then, during step 713 the CPU (or network processor) gets from thecamera object the power profile and the authorized power profiles of theremote camera. The CPU (or network processor) checks whether it ispossible to lower the remote camera power profile (the remote camera isnot in sleep mode and lower power profiles are allowed).

Two strategies may be implemented. According to a first strategy, thepower profile of the cameras is lowered to the minimum until acceptabletotal power consumption is reached. According to a second strategy, thepower profile is changed on an incremental basis per camera in arecurring manner until acceptable total power consumption is reached,for example, the increment is a minimum change of the power profile.

If the remote camera power budget cannot be lowered, then, during step717, the CPU (or network processor) checks whether this was the lastremote camera, from the list of remote cameras attached to the receiverthat might have its power profile lowered.

According to the above first strategy, each camera is tested once,whereas according to the second strategy, each camera can be testedmultiple times.

If there are no more candidate cameras power profile lowering, then,during step 718, the CPU (or network processor) returns a negativeacknowledgement to the sending device (VMS or camera) indicating theimpossibility of changing its own power profile because the receiverpower capacity does not allow it (CPP acknowledgement message 551 withstatus 552 set to KO_RECEIVER). This step ends the power negotiationprocedure.

If there remain cameras that might change their power profile, then theCPU loops back to step 712 to select a new remote camera.

Back to test 713, if the remote camera power profile can be lowered,then, during step 714 the CPU (or network processor) sends a change PPmessage 531 to the remote camera with the PP field 532 set to the lowestauthorized power profile (according to the first strategy) or the nextlowest authorized power profile (according to the second strategy).

According to a third strategy, the CPU (or network processor) maybroadcast the change PP message 531 to all known cameras, thereby savingthe process of selecting the cameras. However, according to thisstrategy, the power consumption decrease may be more drastic thanactually needed if several cameras reduce their consumptionsimultaneously.

Then, during step 715 the CPU waits for an acknowledgment from theremote camera. If no acknowledgement is received, then the CPU loopsback to step 712.

If an acknowledgement is received from the remote camera (CPPacknowledgement 551) with the status 552 OK then, during step 716, theCPU (or network processor) updates the power profile information of theremote camera in the corresponding camera object 412. Then, the CPU (ornetwork processor) loops back to step 710 in order to update the totalreceiver power consumption.

Back to test 711, if the newly calculated total receiver power consumedis not exceeding the receiver maximum power capacity, then:

-   -   concerning the camera embodiments represented by FIGS. 3a, 3b        and those represented by FIG. 3c in which steps flowchart are        executed by the camera CPU 304, the camera CPU (or network        processor) updates, during step 719, the camera power profile in        the camera object 412, and    -   concerning the camera embodiments represented by FIG. 3c in        which steps flowchart are executed by the adapter CPU 304, the        adapter CPU updates, during step 719, the camera power profile        in the camera object 412. Then the adapter CPU sends a “switch        to power profile” message 1830 to the camera with the field        “power profile” 1831 set to the new power profile.

Next, the CPU (or network processor) sends a positive acknowledgementmessage to the requesting device (VMS or camera). It sends a CPPacknowledgement message 551 with the status field 552 set to OK.

During step 721 the CPU (or network processor) then broadcasts a PPupdate message 511 set as follows:

-   -   The message field group id 512 is set with the identification of        the RAM group object 410,    -   The message field port id 513 is set with the identification of        the RAM port object 411 to which the camera is plugged,    -   The message field camera id 514 is set with the identification        of the RAM camera object 412,    -   The message field power profile 515 is set with the power        profile of the RAM camera object 412.

This step ends the power negotiation procedure.

In what follows, the power budget checking performed by the camera CPUthe adapter CPU or the network processor (depending on the implementedembodiment) when it receives a PP info Message is described withreference to the flowchart of exemplary steps of FIG. 8. This processcorresponds to step 613 of FIG. 6.

In order to make easier the reading of the description below concerningthe flowchart, CPU may mean the camera CPU 304, the adapter CPU 304 orthe network processor 322 depending on the implemented embodiment. In asimilar manner, camera elements such RAM, nvRAM may be elements of thecamera (for embodiments represented by FIGS. 3a, 3b and some embodimentsrepresented by FIG. 3c ) or of the adapter (for some embodimentsrepresented by FIG. 3c ) depending on the implemented embodiment.

First, during step 801, the CPU (or network processor) checks whetherthe remote camera is plugged to the same receiver. The CPU (or networkprocessor) compares the group id field 522 of the PP info message 521with the camera group id 402.

If the remote camera is not plugged to the same receiver as the CPU,then there is nothing to be checked by the CPU (or network processor).The process goes to a “no operation” state (step 802), which, byconvention, represents the end of the process.

If the remote camera is plugged to the same receiver as the CPU (ornetwork processor), then, during step 801, the CPU (or networkprocessor) checks whether the remote camera is plugged to the samereceiver port as the CPU (or network processor). The CPU (or networkprocessor) compares the port id field 523 of the PP info message 521with the camera port id 403.

If the remote camera is plugged to the same receiver port as the CPU (ornetwork processor), then, during step 804, the CPU (or networkprocessor) calculates the power consumption of the receiver port, takinginto account the power profile of the new camera. For this purpose, itadds the difference of power consumed by the camera in the current powerprofile and in the new power profile to the field “Total port powerconsumed” of the port object 411.

During test 805, the CPU (or network processor) compares the newcalculated port power consumption with the port maximum power capacity405.

If the port maximum power capacity is exceeded, then step 806 isexecuted. During step 806, the CPU (or network processor) checks whetherit is possible to lower its own power profile (the power profile is notalready set to sleep mode and lower power profiles are allowed).

If the CPU's (or network processor's) own power profile cannot belowered, then, during step 809, the CPU (or network processor) sends analert message 571 to the VMS indicating that the receiver port will notbe able to provide enough power for all cameras (Alert message 571 withGroup id 572 set to Group id 402, Port id 573 set to port id 403, Cameraid 574 set to camera id 401 and status 575 set to PORT). This step 809ends the power budget checking procedure.

Back to test 806, if the CPU (or network processor) own power profilecan be lowered, then during step 807, the CPU (or network processor)updates its own power profile in the camera object 412.

In case of a camera embodiment in which the method of managing power isexecuted in the adapter (FIG. 3c ), during step 807, after the CPU hasbeen updated its own power profile in the camera object 412, the CPUsends a “switch to power profile” message 1830 to the camera with thefield “power profile” 1831 set to the new power profile.

Then, during step 808 the CPU (or network processor) broadcasts a PPupdate message 531 to all cameras in order to inform about its new powerprofile. The Group id field 572 is set to Group id 402, the Port idfield 573 is set to port id 403, the Camera id field 574 is set tocamera id 401 and the PP field 515 is set to the new camera powerprofile. Next, the CPU (or network processor) loops back to step 804 tocheck again the power budget.

Back to test 805, if the port maximum power capacity has not beenreached, then the CPU (or network processor) calculates during step 810the receiver total power consumed by taking into account the remotecamera power profile. For this purpose, it adds the difference of powerconsumed by the camera according to the current power profile andaccording to the new power profile to the field “Total group powerconsumed” of the port object 410.

During test 812 the CPU (or network processor) compares the newcalculated receiver power consumption with the receiver maximum powercapacity 404

If the receiver maximum power capacity is exceeded, then step 814 isexecuted. During step 814 the CPU (or network processor) checks whetherit is possible to lower its own power profile (the camera is not insleep mode and lower power profiles are allowed).

If the CPU (or network processor) own power profile cannot be lowered,then, during step 815, the CPU (or network processor) sends an alertmessage 571 to the VMS indicating that the receiver will not be able toprovide enough power for all cameras (Alert message 571 with Group id572 set to Group id 402, Port id 573 set to port id 403, Camera id 574set to camera id 401 and status 575 set to RECEIVER). This step ends thepower budget checking procedure.

Back to test 814, if the CPU (or network processor) own power profilecan be lowered, then during step 816, the CPU (or network processor)updates its own power profile in the camera object 412.

In case of a camera embodiment in which the method of managing power isexecuted in the adapter (FIG. 3c ), during step 816, after the adapterCPU has been updated its own power profile in the camera object 412, theadapter CPU sends a “switch to power profile” message 1830 to the camerawith the field “power profile” 1831 set to the new power profile.

Next, during step 817, the CPU (or network processor) broadcasts a PPupdate message 531 to all cameras to inform about its new power profile.The Group id field 572 is set to Group id 402, the Port id field 573 isset to port id 403, the Camera id field 574 is set to camera id 401 andthe PP field 515 is set to the new camera power profile. Then the CPU(or network processor) loops back to the step 810 to check again thepower budget.

Back to test 812, if the newly calculated total receiver powerconsumption is not exceeding the receiver maximum power capacity, thenthe CPU (or network processor) has no action perform. The process goesto a “no operation” state (step 813) which represents the end of theprocess.

An exemplary process performed by the CPU of the VMS 101 is describedhereinafter with reference to FIG. 9.

In an initial step 901 the CPU of the VMS waits for a GUI (acronym forGraphical User Interface) action from the user.

If the user modified the GUI panel 200 corresponding to the “adminconfiguration” screen, then, during step 906 the CPU sends an “adminupdate” message 561 with all fields set according to the user's entriesin the screen 200. Next, the CPU loops back to the initial step 901.

If the user acts on the GUI panel 201 part corresponding the cameracontrol screen, then during step 902 the CPU sends a change powerprofile message 531 to the camera that the user has designated. Eachfield of the change PP message 531 is set with the values that the userentered in the GUI.

Next, the CPU waits for the camera acknowledgement (CPP acknowledgement551) during step 903.

When the acknowledgement is received, the CPU checks during test 904 thestatus field 552.

If the status field is “OK”, the VMS CPU loops back to the initial step901.

If the status is not “OK”, then, during step 905, the VMS CPU displaysan error screen 202 if the status is “KO PORT” or an error screen 203 ifthe status is “KO RECEIVER”.

Next, the VMS CPU loops back to the initial step 901.

If there is no GUI action, then the CPU checks during test 907 whetheran alert message has been received.

If no alert message is received, then the CPU loops back to the initialstep 901.

If an alert message is received, then the CPU displays a system errormessage 204 if the status 571 is “PORT” or a system error message 203 ifthe status 571 is “RECEIVER”.

Next, the VMS CPU loops back to the initial step 901.

An exemplary architecture for the VMS 101 is described with reference toFIG. 10.

The VMS comprises a processing unit 1011 connected to I/O devices 1008including for example a mouse and/or a keyboard to allow the operator toact on the GUI which is displayed on a display device 1009.

The processing unit 1011 comprises a CPU 1001 connected to peripheralcontrollers through a communication bus 1002.

The ROM peripheral 1003 is used for storing the CPU programs which maybe designed according to the methods according to embodiments aspresently described, for example with reference to FIG. 9.

When the VMS is started up, the programs are copied from the ROM to theRAM 1004. The CPU gets its instructions and data from the RAM 1004.

The Input peripheral controller 1005 manages the mouse and keyboard. Theinput peripheral drives the mouse and keyboard by implementing forexample USB or PS2 or any other known computer I/O management standard.

The Network Interface Card (NIC) controller 1006 connects the CPU to thenetwork. In this example it is an Ethernet controller and the cable 1010is an Ethernet cable.

The display adapter 1007 drives the display device 1009 by implementingfor example HDMI or DVI or any other known computer graphics standard.

The hard drive 1012 is used for storing permanent data.

In what follows, embodiments are described wherein the power budgetcalculation may be performed by the cameras and the power negotiation bythe VMS.

The data processed by the CPU 1001 of the VMS according to suchembodiments are described with reference to FIG. 11.

The power parameters are stored in the hard drive 1012. These parametersare set at VMS installation time (system setup). They can be overwrittenby the operator during operation when the administrator changes thevalues as a result of device change.

The hard drive parameters include for each camera in the system:

-   -   Camera ID (1101): an identification of the camera    -   Group ID (1102): an identification of the Receiver that provides        the power to the Camera (with the examples of FIGS. 1a and 1b        the cameras 108, 109 and 110 shall be configured with group id        set to Recevier1 while the cameras 113, 112 and 111 have a group        id set to Recevier2).    -   Port ID (1103): an identification of the Receiver port that        provides the power to the camera (with the examples of FIGS. 1a        and 1b the cameras 108 and 109 have a port id set to 2, the        camera 110 have port id set to 4 and the cameras 113, 112 and        111 have a port id set to 3).    -   Group max power (1104): reflects the maximum power that can be        delivered by the Receiver that provides the power to the camera        (IN Figure (with the examples of FIGS. 1a and 1b all cameras        shall have the group max power set to 250 watt).    -   Port max power (1105): reflects the maximum power that can be        delivered by the port of the Receiver that provides the power to        the camera (with the examples of FIGS. 1a and 1b all cameras        shall have the group max power set to 75 watt).    -   Default power profile (1106): defines the power profile of the        camera after a cycle power on. Four possible profiles are        described as an illustration of the invention:        -   PTZ: the camera movements are allowed including the optical            zoom setup,        -   Hi_res: the camera can be set to the highest image            resolution, camera movements are not allowed,        -   Lo_res: the camera cannot be set to high resolution and the            camera movements are not allowed,        -   Sleep: the mare is not allowed to stream video and the            camera movement are not allowed.    -   Authorized power profiles (1107): defines the power profile that        the administrator wants to authorise for the camera. For        example, if an administrator wants that the camera is never in        sleep mode and it doesn't care about the resolution and the        ability to move, then the administrator will set (1,1,1,0) as        the authorized power profiles.    -   Power consumption (1108): defines the camera power consumption        in the different profiles:        -   P_PTZ: power consumed by the camera when in PTZ profile,        -   P_HI_res: power consumed by the camera when in Hi_res            profile,        -   P_Lo_res: power consumed by the camera when in Lo_res            profile,        -   P_Sleep: power consumed by the camera when in Sleep profile.

During runtime the CPU 1001 of the VMS processes the available powerbudget and its own power profile by maintaining a data structure in theRAM 1004. This data structure comprises one Group object for eachReceiver in the system, each group object contains:

-   -   The group ID as set in the Group ID 1102,    -   The total group power consumed: the sum of the power profiles of        all the camera connected to the Receiver,    -   Pointer to port objects: each port of the Receiver is        represented by a port object 1111.

The port object 1111 contains:

-   -   The port ID as set in the Port ID 1103,    -   The total port power consumed: the sum of the power profiles of        all the camera connected to the Receiver port,    -   Pointer to camera object: each camera is represented by a camera        object 1112.

The camera object 1112 contains:

-   -   The camera ID: local identification as set in the Camera ID 1101        or the identification of the other cameras as the CPU is        receiving Network join messages 501 or PP info message 521.    -   The Power profile: as set in the Default Power Profile 1106, or        as modified by the VMS (Change PP message 531) for a local        camera or as set in Network join messages 501 or PP info message        521 from other camera,    -   Authorized power profile: as set in the Authorized power        profiles 1107 or as modified by the VMS (Change APP message 551)        for a local camera, or as set in Network join messages 501 from        other cameras,    -   Power consumption information as set in the Power Consumption        1108.

The power negotiation by the VMS is described with reference to theflowchart of FIG. 12. Some steps of the flowchart of FIG. 12 are thesame as those of the flowchart of FIG. 9, the references used in FIG. 12are thus the same as in FIG. 9 for these common steps.

In an initial step 901, the CPU of the VMS waits for a GUI action fromthe user.

If the user acts on the GUI panel 200 part corresponding to theadministration configuration, then the steps and actions executed by theCPU are those described with reference to FIG. 9.

If the user does not act on the GUI actions, then the steps and actionsexecuted by the VMs CPU are described with reference to FIG. 9.

If the user acts on the GUI panel 201 part corresponding to the cameracontrol, then during step 902, the CPU of the VMS sends a change powerprofile message 531 to the camera that the user has designated. Eachfield of the change PP message 531 is set with the values entered by theuser in the GUI.

Next, the CPU waits for the camera acknowledgement (CPP acknowledgement551) during step 903.

When the acknowledgement is received, the CPU checks during test 904 thestatus field 552.

If the status field is “OK”, the CPU loops back to the initial step 901.

If the status is not “OK”, then, during test 1202, the CPU checkswhether the status is “PORT_KO” (port power capacity is exceeded).

If the port maximum power capacity is exceeded, then, step 1203 isexecuted. During step 1203, the CPU gets a camera object 1112 of asecond camera from the list of camera objects linked to the same portobject 1111 as the camera selected by the operator during the previousstep 901.

Alternatively, during step 1203, the CPU can ask the operator to selecta candidate camera for power profile reduction.

Next, during step 1204, the CPU gets from the camera object the powerprofile and the authorized power profiles of the second camera. The CPUchecks whether it is possible to lower the second camera power profile(the remote camera is not in sleep mode and lower power profiles areallowed).

According to a first strategy, the power profile of the cameras islowered to the minimum until acceptable total power consumption isreached. According to a second strategy, the power profile is changed onan incremental basis per camera in a recurring manner until acceptabletotal power consumption is reached, for example, the increment is aminimum change of the power profile.

If the second camera power profile cannot be lowered, then, during step1208, the CPU checks whether this was the last remote camera from thelist of remote cameras attached to the receiver port that might have itspower profile lowered.

According to the first strategy, each camera is tested once, whereas forthe second strategy, each camera can be tested several times.

If there are no more candidate cameras for power profile lowering, then,during step 1209, the CPU displays an error message 202 indicating theimpossibility of changing the power profile of the camera because thereceiver port power capacity does not allow it. This step ends the powernegotiation procedure. The CPU then loops back the initial step 901.

If there remain cameras that might change their power profile, then theCPU loops back to step 1203 to select a new camera.

Back to test 1204, if the remote camera power profile can be lowered,then, during step 1205, the CPU sends a change PP message 531 to thesecond camera with the PP field 532 set to the lowest authorized powerprofile (for the first strategy) or the next lowest authorized powerprofile (for the second strategy).

According to a third strategy, the CPU may broadcast the change PPmessage 531 to all known cameras, thereby saving the process ofselecting the cameras. However, according to this strategy, the powerconsumption decrease may be more drastic than actually needed.

Next, during step 1206 the CPU waits for an acknowledgment from theremote camera. If no acknowledgement is received, then, the CPU loopsback to step 1203.

If an acknowledgement is received from the second camera (CPPacknowledgement 551) with the status 552 OK, then, the CPU updates thepower profile information of the remote camera in the correspondingcamera object 1112. The CPU loops back to step 902 in order to sendagain the change PP message to the camera selected by the operatorduring the previous step 901.

Back to test 1202, if the receiver maximum power capacity is exceeded,then step 1212 is executed. During step 1212, the CPU gets a cameraobject 1112 of a second camera from the list of camera objects linked tothe same receiver object 1110 as the camera selected by the operatorduring the previous step 901.

Alternatively, during step 1212, the CPU may ask the operator to selecta candidate camera for power profile reduction.

Next, during step 1213, the CPU gets from the camera object the powerprofile and the authorized power profiles of the second camera. The CPUchecks whether it is possible to lower the second camera power profile(the second camera is not in sleep mode and lower power profiles areallowed).

According to a first strategy, the power profile of the cameras islowered to the minimum until acceptable total power consumption isreached. According to a second strategy, the power profile is changed onan incremental basis per camera in a recurring manner until acceptabletotal power consumption is reached, for example, the increment is aminimum change of the power profile.

If the second camera power budget cannot be lowered, then, during step1217, the CPU checks whether this was the last camera from the list ofcameras attached to the receiver that might have its power profilelowered

According to the first strategy, each camera is tested once, whereasaccording to the second strategy, each camera may be tested severaltimes.

If there are no more candidate cameras for power profile lowering, then,during step 1218, the CPU displays an error message 203 indicating theimpossibility of changing the power profile of the camera because thereceiver power capacity does not make it possible. This step ends thepower negotiation procedure. The CPU then loops back to the initial step901.

If there remain cameras that might change their power profile, then theCPU loops back to step 1212 to select a new remote camera.

Back to test 1213, if the second camera power profile can be lowered,then, during step 1214, the CPU sends a change PP message 531 to thesecond camera with the PP field 532 set to the lowest authorized powerprofile (according to the first strategy) or the next lowest authorizedpower profile (according to the second strategy).

According to a third strategy, the CPU may broadcast the change PPmessage 531 to all known cameras thereby saving the process of selectingthe cameras. However, according to this strategy, the power consumptiondecrease may be more drastic than actually needed.

Next, during step 1215, the CPU waits for an acknowledgment from theremote camera. If no acknowledgement is received, then the CPU loopsback to step 1212.

If an acknowledgement is received from the remote camera (CPPacknowledgement 551) with the status 552 OK, then, during step 1216, theCPU updates the power profile information of the remote camera in thecorresponding camera object 1112. Next, the CPU loops back to step 1210in order to update the total receiver power consumption.

If an acknowledgement is received from the second camera (CPPacknowledgement 551) with the status 552 OK, then, the CPU updates thepower profile information of the remote camera in the correspondingcamera object 1112. The CPU loops back to the step 902 to send again thechange PP massage to the camera selected by the operator during theprevious step 901.

An exemplary power budget calculation by the CPU of a camera or of anadapter, or by a network processor (depending in the implementedembodiment) is described in what follows with reference to the flowchartof FIG. 13. This calculation is an implementation of step 605 in FIG. 6.

First, during step 1301, the CPU calculates the new total power consumedby the receiver port, taking into account the new power profile wantedfor the camera. For this purpose, it adds the difference of powerconsumed by the camera according to the current power profile andaccording to the new power profile to the field “Total port powerconsumed” of the port object 411.

During test 1302, the CPU compares the new calculated port powerconsumption with the port maximum power capacity 405.

If the port maximum power capacity is exceeded, then, during step 1309,the CPU returns a negative acknowledgement to the sending device (VMS orcamera) indicating the impossibility of changing its own power profilebecause the receiver port power capacity does not allow it (CPPacknowledgement message 551 with status 552 set to KO_PORT). This stepends the power negotiation procedure.

Back to test 1302, if the port maximum power capacity has not beenreached, then, the CPU calculates during step 1310 the receiver totalpower consumed by taking into account the camera new requested powerprofile. For this purpose it adds the difference of power consumed bythe camera according to the current power profile and according to thenew power profile to the field “Total group power consumed” of the portobject 410.

During test 1311, the CPU compares the new calculated receiver powerconsumed with the receiver maximum power capacity 404.

If the receiver maximum power capacity is exceeded, then, during step1318, the CPU returns a negative acknowledgement to the sending device(VMS or camera) indicating the impossibility of changing its own powerprofile because the receiver power capacity does not allow it (CPPacknowledgement message 551 with status 552 set to KO_RECEIVER). Thisstep ends the power negotiation procedure.

Back to test 1311, if the newly calculated total receiver power consumedis not exceeding the receiver maximum power capacity, then the CPUupdates, during step 1319, the camera power profile in the camera object412.

Next, the CPU sends a positive acknowledgement message during step 1320,to the requesting device (VMS or camera). It sends a CPP acknowledgementmessage 551 with the status field 552 set to OK.

Next, during step 1321, the CPU broadcasts a PP update message 511 setas follows:

-   -   The message field group id 512 is set with the identification of        the RAM group object 410,    -   The message field port id 513 is set with the identification of        the RAM port object 411 to which the camera is plugged,    -   The message field camera id 514 is set with the identification        of the RAM camera object 412,    -   The message field power profile 515 is set with the power        profile of the RAM camera object 412.

This step ends the power negotiation procedure.

In what follows, embodiments are described wherein the power budgetcalculation and the power negotiation are performed by the VMS. Suchembodiments are described with reference to the flowchart of FIG. 14.

The initial step 901 is the same as in FIG. 9, the CPU waits for a GUIaction from the user.

If the user acts on the part of the GUI panel 200 that corresponds tothe “admin configuration” screen, then the steps and actions executed bythe CPU are those described with reference to FIG. 9.

If there was no GUI action, then the steps and actions executed by theCPU are also those described with reference to FIG. 9.

If the user acts on the part of the GUI panel 201 that corresponds tothe camera control screen, then, during step 1401, the CPU calculatesthe new total power consumed by the receiver port taking into accountthe new power profile wanted for the selected camera. For this purpose,it adds the difference of power consumed by the camera according to thecurrent power profile and according to the new power profile to thefield “Total port power consumed” of the port object 1111.

During test 1402, the CPU compares the new calculated port powerconsumption with the port maximum power capacity 1105.

If the port maximum power capacity is exceeded, then step 1403 isexecuted. During step 1403, the CPU gets a camera object 1112 of asecond camera from the list of camera objects linked to the same portobject 1111 as the camera selected by the operator during the previousstep 901.

Alternatively, during step 1403, the CPU may ask the operator to selecta candidate camera for power profile reduction.

Next, during step 1404, the CPU gets from the camera object the powerprofile and the authorized power profiles of the second camera. The CPUchecks whether it is possible to lower the second camera power profile(the remote camera is not in sleep mode and lower power profiles areallowed). Two strategies can be implemented with regards to theinvention.

According to a first strategy, the power profile of the cameras islowered to the minimum until acceptable total power consumption isreached. According to a second strategy, the power profile is changed onan incremental basis per camera in a recurring manner until acceptabletotal power consumption is reached, for example, the increment is aminimum change of the power profile.

If the second camera power profile cannot be lowered, then, during step1408, the CPU checks whether this was the last remote camera from thelist of remote cameras attached to the receiver port that might have itspower profile lowered. According to the first strategy, each camera istested once, whereas for the second strategy, each camera can be testedseveral times.

If there are no more candidate cameras for power profile lowering, then,during step 1409, the CPU displays an error message 202 indicating theimpossibility of changing the power profile of the camera because thereceiver port power capacity does not allow it. This step ends the powernegotiation procedure. Next, the CPU loops back the initial step 901.

If there remain cameras that might change their power profile, then theCPU loops back to step 1403 to select a new second camera.

Back to test 1404, if the remote camera power profile can be lowered,then, during step 1405, the CPU sends a change PP message 531 to thesecond camera with the PP field 532 set to the lowest authorized powerprofile (for the first strategy) or the next lowest authorized powerprofile (for the second strategy).

According to a third strategy, the CPU may broadcast the change PPmessage 531 to all known cameras, thereby saving the process ofselecting the cameras. However, according to this strategy, the powerconsumption decrease may be more drastic than actually needed.

Next, during step 1406, the CPU waits for an acknowledgment from thesecond camera. If no acknowledgement is received, then the CPU loopsback to step 1403.

If an acknowledgement is received from the second camera (CPPacknowledgement 551) with the status 552 OK, then during step 1407 theCPU updates the power profile information of the second camera in thecorresponding camera object 1112. Next, the CPU loops back to step 1401in order to update the total port power consumed.

Back to test 1402, if the port maximum power capacity has not beenreached, then the CPU calculates during step 1410 the receiver totalpower consumed by taking into account the camera new requested powerprofile. For this purpose, it adds the difference of power consumed bythe camera according to the current power profile and according to thenew power profile to the field “Total group power consumed” of the portobject 1110.

During test 1411, the CPU compares the new calculated receiver powerconsumed with the receiver maximum power capacity 1104.

If the receiver maximum power capacity is exceeded, then the step 1412is executed. During step 1412 the CPU gets a camera object 1112 of asecond camera from the list of camera objects linked to the samereceiver object 1110 as the camera selected by the operator during theprevious step 901.

Alternatively, during step 1212 the CPU may prompt the operator toselect a candidate camera for power profile reduction.

Next, during step 1413 the CPU gets from the camera object the powerprofile and the authorized power profiles of the second camera. The CPUchecks whether it is possible to lower the second camera power profile(the second camera is not in sleep mode and lower power profiles areallowed).

According to a first strategy, the power profile of the cameras islowered to the minimum until acceptable total power consumption isreached. According to a second strategy, the power profile is changed onan incremental basis per camera in a recurring manner until acceptabletotal power consumption is reached, for example, the increment is aminimum change of the power profile.

If the second camera power budget cannot be lowered, then during step1417 the CPU checks whether this was the last second camera from thelist of second cameras attached to the receiver that might have itspower profile lowered. According to the first strategy, each camera istested once, whereas for the second strategy, each camera can be testedseveral times.

If there are no more candidate cameras for power profile lowering, thenduring step 1418, the CPU returns a negative acknowledgement to thesending device (VMS or camera) indicating the impossibility of changingits own power profile because the receiver power capacity does not allowit (CPP acknowledgement message 551 with status 552 set to KO_RECEIVER).This step ends the power negotiation procedure.

If there are no more candidate cameras for power profile lowering, then,during step 1218, the CPU displays an error message 203 indicating theimpossibility of changing the power profile of the camera because thereceiver power capacity does not allow it. This step ends the powernegotiation procedure. The CPU loops back the initial step 901.

If there remain cameras that might change their power profile, then, theCPU loops back to step 1412 to select a new second camera.

Back to test 1413, if the second camera power profile can be lowered,then during step 1414 the CPU sends a change PP message 531 to thesecond camera with the PP field 532 set to the lowest authorized powerprofile (for the first strategy) or the next lowest authorized powerprofile (for the second strategy).

According to a third strategy, the CPU may broadcast the change PPmessage 531 to all known cameras, thereby saving the process ofselecting the cameras. However, according to this strategy, the powerconsumption decrease may be more drastic than actually needed.

Next, during step 1415 the CPU waits for an acknowledgment from thesecond camera. If no acknowledgement is received, then the CPU loopsback to step 1412.

If an acknowledgement is received from the second camera (CPPacknowledgement 551) with the status 552 OK then during the step 1416the CPU updates the power profile information of the second camera inthe corresponding camera object 1112. Then the CPU loops back to step1410 in order to update the total receiver power consumption.

Back to test 1411, if the newly calculated total receiver power consumedis not exceeding the receiver maximum power capacity, then, the CPUupdates during step 1419 the camera power profile in the camera object1112.

Next, during step 1420 the CPU of the VMS sends a change power profilemessage 531 to the camera that the user has designated during the firststep 901. Each field of the change PP message 531 is set with the valuesentered by the user in the GUI. There is no need to wait for anacknowledgment here since the CPU has performed the power budgetcalculation and power negotiation in the previous steps.

This step ends the power negotiation procedure and the CPU loops back tothe initial step 901.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, such illustration and descriptionare to be considered illustrative or exemplary and not restrictive, theinvention being not restricted to the disclosed embodiment. Othervariations to the disclosed embodiment can be understood and effected bythose skilled in the art in practicing the claimed invention, from astudy of the drawings, the disclosure and the appended claims.

In the claims, the word “comprising” does not exclude other elements orsteps, and the indefinite article “a” or “an” does not exclude aplurality. The mere fact that different features are recited in mutuallydifferent dependent claims does not indicate that a combination of thesefeatures cannot be advantageously used. Any reference signs in theclaims should not be construed as limiting the scope of the invention.

The invention claimed is:
 1. A method of managing power in a power overdata network, the method comprising the following steps: obtaining afirst request for modification of a power consumption profile of adevice connected to the network, a power negotiation procedurecomprising: when the modification entails a raise in the powerconsumption profile, determining whether the first request can besatisfied with regards to a current consumption situation over thenetwork, and wherein, when it is determined that the first requestcannot be satisfied: triggering a broadcast over the network of a secondrequest for lowering a power consumption profile of at least one deviceconnected to the network when it is determined that the first requeststill cannot be satisfied, ending the negotiation procedure by returninga negative acknowledgement indicating that the first request cannot beallowed.
 2. The method according to claim 1, wherein when themodification entails a drop in the power consumption, or when it isdetermined that the first request can be satisfied, the method comprisestriggering: the modification of the power consumption profile, and abroadcast of a message over the network identifying the modification ofthe power consumption profile.
 3. The method according to claim 2,wherein the triggering of the modification of the power consumptionprofile comprises sending a request for modification of the powerconsumption profile to the device connected to the network.
 4. Themethod according to claim 1, wherein the triggering of a broadcast overthe network of a second request for lowering a power consumption profilecomprises emitting a message indicating that the first request cannot besatisfied.
 5. The method according to claim 1, wherein the networkcomprises a plurality of devices controlled by a control device, andwherein the method is carried out by each of the devices.
 6. The methodaccording to claim 1, wherein the network comprises a plurality ofdevices controlled by a control device, and wherein the method iscarried out by the control device.
 7. The method according to claim 4,wherein the network comprises a plurality of devices controlled by acontrol device, and wherein the message indicating that the firstrequest cannot be satisfied is sent by a device to the control device,the broadcast over the network of a second request for lowering a powerconsumption profile is sent by the device and the other steps arecarried out by the devices.
 8. The method according to claim 1 furthercomprising the following steps, when a device is newly connected to thenetwork: broadcasting a message comprising power profile characteristicsof the device newly connected to the network, receiving, in response tothe message, at least one power profile information message from atleast one device connected to the network, the at least one powerprofile information message comprising power profile informationconcerning the at least one device connected to the network, anddetermining a current consumption situation over the network based onthe received at least one power profile information message from atleast one device connected to the network.
 9. The method according toclaim 8, further comprising: determining whether it is possible to lowerthe power profile of the device newly connected to the network withregards to the determined current consumption situation over thenetwork, and if the power profile cannot be lowered, emitting an alertmessage indicating that at least one power consumption will not besatisfied on the network.
 10. A method of managing power in a power overdata network, the method comprising the following steps, performed by amonitoring device of the network: determining that a first request formodification of the power consumption profile of a device connected tothe network cannot be satisfied, when said modification entails a raisein said power consumption profile, and repeatedly broadcasting over thenetwork a second request for lowering the power consumption profiles ofthe other devices connected to the network.
 11. The method according toclaim 10, wherein the determining step comprises receiving, from thedevice connected to the network, a message indicating the first requestfor modification of its power consumption profile cannot be satisfied.12. The method according to claim 10, further comprising transmitting tothe device connected to the network, a message indicating that the firstrequest can be satisfied.
 13. The method according to claim 1, whereinthe method is performed by a device connected to the network.
 14. Themethod according to claim 13, wherein the triggering step comprises:transmitting to a monitoring device of the network a message indicatingthat the first request cannot be satisfied with regards to the currentconsumption situation over the network, thereby enabling the monitoringdevice to perform the broadcasting, and receiving, in response to themessage, a message indicating that the first request can be satisfied.15. The method according to claim 13, wherein the device connected tothe network comprises a camera device.
 16. The method according to claim15, wherein the device connected to the network further comprises anetwork adapter connected to the camera device by a communication link.17. A method according to claim 16, wherein the method furthercomprising: the camera device sending a first message to the networkadapter, and the network adapter sending in response to the message, asecond message comprising the power consumption of the network adapter.18. A device of managing power in a power over data network, the devicecomprising: means for obtaining a first request for modification of apower consumption profile of the device, the device being connected tothe network, means for determining whether the first request can besatisfied with regards to a current consumption situation over thenetwork, when the modification entails a raise in the power consumptionprofile, and means for triggering a broadcast over the network of asecond request for lowering a power consumption profile of at least onedevice connected to the network when means for determining determinethat the first request cannot be satisfied.
 19. A device for managingpower in a power over data network, the device further comprising: meansfor determining that a first request for modification of the powerconsumption profile of a device connected to the network cannot besatisfied, when the modification entails a raise in the powerconsumption profile, and means for repeatedly broadcasting over thenetwork a second request for lowering the power consumption profiles ofthe other devices connected to the network, the second request beingrepeatedly broadcasted until the first request can be satisfied.
 20. Adevice performing the method for managing power according to claim 1;wherein the device comprises a camera device and a network adapterconnected to the camera device by a communication link.
 21. The deviceaccording to claim 20, wherein the camera device comprises: means forsending a first message to the network adapter, and means for receivingin response to the first message, a second message comprising the powerconsumption of the network adapter.
 22. Network adaptor connected to acamera device by a communication link, the network adaptor comprisingmeans for sending a message to the camera device containing a new powerprofile when the camera device receives a request for modification ofpower consumption profile.
 23. A non-transitory computer-readablestorage medium storing instructions of a computer program forimplementing a method for managing power according to claim
 10. 24. Amethod according to claim 1, wherein the method further comprisesgetting back to the determination step after the broadcasting.